Several tactical options are available to police officers facing potentially aggressive or violent people or those with acute behavioural disturbance. The less lethal options include restraint, batons, incapacitant sprays, impact rounds, and conducted energy devices such as Tasers. Although none is risk free, Tasers have attracted particular controversy, with Amnesty International identifying more than 300 deaths associated with their use in the United States.1 However, association is not causation, and other factors complicate the interpretation of fatal outcomes.

The dominant conducted energy device used in police forces worldwide is the Taser X26. This device generates five second trains of electrical pulses that are delivered to the body either by two propelled barbs (which embed in clothing or skin and remain connected to the handset by conductive wire) or by direct contact of the handset’s electrodes (drive-stun mode).2 In the United Kingdom, propelled barbs are used by police in 90% of incidents in which such a device is discharged.3 Anecdotal evidence indicates that the threat of discharge alone may be an effective deterrent.3

In drive-stun mode, the principal action of the discharge is to induce pain (designed to gain the subject’s compliance). When the barbs are propelled, greater electrode separation facilitates the induction of involuntary (and painful) contraction of skeletal …

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